Gravity/inertia actuated latch elements of conventional simple one-piece construction are normally pivotally mounted on a forward tiltable seat back to engage a forward latch stop which may be on a fixed or on an angularly adjustable element of a recliner hinge which will inherently provide different angular latch stop positions for corresponding adjusted positions of the operative seat back angle. This together with extremities of vehicle inclination under either a parked condition where gravity actuated release is required or a driving condition where emergency inertia latch lock is required, impose a range of parameters which are not readily solved with any simple one-piece inertia latch wherein the range of angularity of the center of gravity of the latch relative to its pivot center provides an effective moment arm for each of the relatively opposing moments responsive to gravity and inertia which is a simple function of polar coordinates relative to horizontal and vertical lines extending from the pivot center.
Furthermore, with a single piece latch construction having adequate strength under latch engagement to resist maximum passenger loads against the seat back under crash deceleration conditions, inherent minimum limits of articulation between fully engaged and release positions as well as latch extensions for imposing a latch engagement orientation when the seat back is in operative position involve substantial inherent weight requirements for the inertia latch in order to achieve the limited optimum dependability which may be possible with a single piece inertia latch system.